3,337 research outputs found
Nonlocality as a Benchmark for Universal Quantum Computation in Ising Anyon Topological Quantum Computers
An obstacle affecting any proposal for a topological quantum computer based
on Ising anyons is that quasiparticle braiding can only implement a finite
(non-universal) set of quantum operations. The computational power of this
restricted set of operations (often called stabilizer operations) has been
studied in quantum information theory, and it is known that no
quantum-computational advantage can be obtained without the help of an
additional non-stabilizer operation. Similarly, a bipartite two-qubit system
based on Ising anyons cannot exhibit non-locality (in the sense of violating a
Bell inequality) when only topologically protected stabilizer operations are
performed. To produce correlations that cannot be described by a local hidden
variable model again requires the use of a non-stabilizer operation. Using
geometric techniques, we relate the sets of operations that enable universal
quantum computing (UQC) with those that enable violation of a Bell inequality.
Motivated by the fact that non-stabilizer operations are expected to be highly
imperfect, our aim is to provide a benchmark for identifying UQC-enabling
operations that is both experimentally practical and conceptually simple. We
show that any (noisy) single-qubit non-stabilizer operation that, together with
perfect stabilizer operations, enables violation of the simplest two-qubit Bell
inequality can also be used to enable UQC. This benchmarking requires finding
the expectation values of two distinct Pauli measurements on each qubit of a
bipartite system.Comment: 12 pages, 2 figure
Note and Comment
Ignorance and Mistake of Law Caused by Over-Ruled Cases; The Doctrine of Exemplary Damages in Its Application to Corporations; When is a Will Signed At the End? : Construction of the Code Phrase Subject of Actio
Noise Thresholds for Higher Dimensional Systems using the Discrete Wigner Function
For a quantum computer acting on d-dimensional systems, we analyze the
computational power of circuits wherein stabilizer operations are perfect and
we allow access to imperfect non-stabilizer states or operations. If the noise
rate affecting the non-stabilizer resource is sufficiently high, then these
states and operations can become simulable in the sense of the Gottesman-Knill
theorem, reducing the overall power of the circuit to no better than classical.
In this paper we find the depolarizing noise rate at which this happens, and
consequently the most robust non-stabilizer states and non-Clifford gates. In
doing so, we make use of the discrete Wigner function and derive facets of the
so-called qudit Clifford polytope i.e. the inequalities defining the convex
hull of all qudit Clifford gates. Our results for robust states are provably
optimal. For robust gates we find a critical noise rate that, as dimension
increases, rapidly approaches the the theoretical optimum of 100%. Some
connections with the question of qudit magic state distillation are discussed.Comment: 14 pages, 1 table; Minor changes vs. version
Impact of dysfunctional maternal personality traits on risk of offspring depression, anxiety and self-harm at age 18 years:a population-based longitudinal study
BackgroundThe impact of underlying parental psychological vulnerability on the future mental health of offspring is not fully understood. Using a prospective cohort design, we investigated the association between dysfunctional parental personality traits and risks of offspring self-harm, depression and anxiety.MethodsThe association between dysfunctional parental personality traits (monotony avoidance, impulsivity, anger, suspicion, and detachment), measured in both mothers and fathers when offspring were age 9 years, and risk of offspring depression, anxiety and self-harm at age 18 years, was investigated in a population-based cohort (ALSPAC) from over 8000 parents and children.ResultsHigher levels of dysfunctional maternal, but not paternal, personality traits were associated with an increased risk of self-harm, depression, and anxiety in offspring. Maternal associations were best explained by the accumulation of dysfunctional traits. Associations were strongest for offspring depression: Offspring of mothers with three or more dysfunctional personality traits were 2.27 (1.45–3.54, p < 0.001) times as likely to be depressed, compared with offspring of mothers with no dysfunctional personality traits, independently of maternal depression and other variables.ConclusionsThe accumulation of dysfunctional maternal personality traits is associated with the risk of self-harm, depression, anxiety in offspring independently of maternal depression and other confounding variables. The absence of associations for equivalent paternal traits makes a genetic explanation for the findings unlikely. Further research is required to elucidate the underlying mechanism. Mothers with high levels of dysfunctional personality traits may benefit from additional support to reduce the risk of adverse psychological outcomes occurring in their offspring.</jats:sec
Recommended from our members
A study of physician acceptance of a prescription pharmaceutical innovation within a selected Oregon community
An investigation concerning the acceptance of a new, legend drug
product was conducted within a community of 15,000 population.
Twenty-eight physicians within the community were chosen for evaluation
relative to acceptance of the new drug product.
Data were obtained by means of a prescription audit of nine retail
pharmacies in the community. The time period of the audit consisted
of three months prior, and nine months subsequent, to the
introduction of the new drug product.
A descriptive analysis of the selected pharmaceutical market
indicated a seasonal variation in utilization of the class of drug products
to which the new drug product belonged. A high degree of substitutability
was also indicated for drug products within the special
class.
A rank-order analysis indicated physician general prescribing
frequency and physician class prescribing frequency were positively
correlated.
Definitions of acceptance of the new drug product were constructed
by means of objective criteria. These criteria were implemented by
utilizing physician prescribing records, market share information,
and a linear, least squares regression equation.
Certain physician characteristics were found to be positively
correlated with early acceptance of the new drug product. These
characteristics pertained to class prescribing frequency, general
prescribing frequency, and medical school alma mater location.
Pharmacists within the community were selected for evaluation
as an alternate source of market information. A mail questionnaire
was constructed and from its responses eight physician classifications
were established. Six of the classifications were positively
correlated with early acceptance of the new drug product. The
strengths of correlation of two questionnaire classifications were
equal to the strongest correlation achieved using prescription audit
data
Application of a Resource Theory for Magic States to Fault-Tolerant Quantum Computing
Motivated by their necessity for most fault-tolerant quantum computation schemes, we formulate a resource theory for magic states. First, we show that robustness of magic is a well-behaved magic monotone that operationally quantifies the classical simulation overhead for a Gottesman-Knill-type scheme using ancillary magic states. Our framework subsequently finds immediate application in the task of synthesizing non-Clifford gates using magic states. When magic states are interspersed with Clifford gates, Pauli measurements, and stabilizer ancillas—the most general synthesis scenario—then the class of synthesizable unitaries is hard to characterize. Our techniques can place nontrivial lower bounds on the number of magic states required for implementing a given target unitary. Guided by these results, we have found new and optimal examples of such synthesis
Supersymmetry discovery potential of the LHC at 10 and 14 TeV without and with missing
We examine the supersymmetry (SUSY) reach of the CERN LHC operating at
and 14 TeV within the framework of the minimal supergravity
model. We improve upon previous reach projections by incorporating updated
background calculations including a variety of Standard Model (SM)
processes. We show that SUSY discovery is possible even before the detectors
are understood well enough to utilize either or electrons in
the signal. We evaluate the early SUSY reach of the LHC at TeV by
examining multi-muon plus jets and also dijet events with {\it no}
missing cuts and show that the greatest reach in terms of
occurs in the dijet channel. The reach in multi-muons is slightly smaller in
, but extends to higher values of . We find that an observable
multi-muon signal will first appear in the opposite-sign dimuon channel, but as
the integrated luminosity increases the relatively background-free but
rate-limited same-sign dimuon, and ultimately the trimuon channel yield the
highest reach. We show characteristic distributions in these channels that
serve to distinguish the signal from the SM background, and also help to
corroborate its SUSY origin. We then evaluate the LHC reach in various
no-lepton and multi-lepton plus jets channels {\it including} missing
cuts for and 14 TeV, and plot the reach for integrated
luminosities ranging up to 3000 fb at the SLHC. For TeV,
the LHC reach extends to and 2.9 TeV for
and integrated luminosities of 10, 100, 1000 and
3000 fb, respectively. For TeV, the LHC reach for the same
integrated luminosities is to m_{gluino}=2.4,\3.1, 3.7 and 4.0 TeV.Comment: 34 pages, 25 figures. Revised projections for the SUSY reach for
ab^-1 integrated luminosities, with minor corrections of references and text.
2 figures added. To appear in JHE
Reach of the Fermilab Tevatron for minimal supergravity in the region of large scalar masses
The reach of the Fermilab Tevatron for supersymmetric matter has been
calculated in the framework of the minimal supergravity model in the clean
trilepton channel. Previous analyses of this channel were restricted to scalar
masses m_0<= 1 TeV. We extend the analysis to large values of scalar masses
m_0\sim 3.5 TeV. This includes the compelling hyperbolic branch/focus point
(HB/FP) region, where the superpotential \mu parameter becomes small. In this
region, assuming a 5\sigma (3\sigma) signal with 10 (25) fb^{-1} of integrated
luminosity, the Tevatron reach in the trilepton channel extends up to
m_{1/2}\sim 190 (270) GeV independent of \tan\beta . This corresponds to a
reach in terms of the gluino mass of m_{\tg}\sim 575 (750) GeV.Comment: 11 page latex file including 6 EPS figures; several typos corrected
and references adde
- …